I'm also intrigued why on earth you would use 20 or more distros? I found one good one and settled on it.

I like to experiment. Many of the distros that I tried out were in the process of finding something that I liked for use on my old Asus Eee PC 4G Surf netbook.

That said, I still run several different distros. I have a machine that I use to download, store, and burn distro ISOs to CD/DVD. That machine is loaded with TinyMe, a PCLinuxOS variant. My ThinkPad is running Ubuntu Intrepid (8.10), which until just recently, was the current, up-to-date version of Ubuntu. The Eee was replaced by an Acer Aspire One (160GB HDD version). This machine dual boots XP and Ubuntu Jaunty Netbook Remix. I've been running Jaunty on it since it was at the Alpha level. On the Windows side of this machine, I run Mozilla Minefield. I have one more machine, this a full-sized Acer laptop the dual boots Vista (yuck!) and Windows 7 (Vista SE). I am involved in an official Beta Test of Win7. On Vista, I use Firefox 3.5 Beta 4, having recently upgraded from 3.1 Beta 3.

EDIT: I should note that I earn my living off providing desktop/server support and that is why I have/try such a variance of systems.